Nowadays, in image display apparatuses such as monitors of personal computers, TV sets and the like, use of TFT driving display apparatuses in a vertically aligned (VA) mode has increased. This VA mode has unfavorable characteristics in which a contrast from an oblique direction deteriorates and tone reversal occurs at a black displaying part while displaying in black (while applying an electric charge). In order to improve this angular dependence of display quality, an optical film including a birefringent film such as a retardation plate that shows an optical biaxiality is generally disposed between two polarizing plates in a liquid crystal panel.
The birefringent film with an optical biaxiality may be manufactured by a method using a polymer material such as polyimide or the like, more specifically, a method including the steps of coating a base with a polymer solution obtained by dissolving the polymer material in a solvent; drying the thus obtained coating film so as to form a birefringent film with an optical negative uniaxiality; and stretching the birefringent film so as to obtain a birefringent film with an optical biaxiality, is disclosed (for example, see JP8(1996)-511812A). Also, a method for manufacturing the birefringent film with an optical biaxiality having high uniformity, which can control distribution of a refractive index easily, is disclosed (for example, see JP2000-190385A).